Preparation method of steel-copper alloy composite material

Abstract

The invention provides a preparation method of a steel-copper alloy composite material. The method comprises the following steps: preparing raw materials; copper alloy smelting is conducted, specifically, electrolytic copper, zinc, aluminum, manganese and iron are put into a power frequency induction furnace in proportion, the heating temperature ranges from 1150 DEG C to 1200 DEG C, the heat preservation time ranges from 30 min to 40 min, and molten copper alloy is obtained after smelting; steel pretreatment; the preheated steel is put into a mold, molten copper alloy is cast at the casting speed of 0.5-1 kg / s, cooling treatment is conducted through a subsection cooling method after casting, the temperature ranging from 800 DEG C to 600 DEG C is a slow cooling stage, the cooling speed ranges from 5 DEG C / min to 10 DEG C / min, and the temperature below 600 DEG C is a rapid cooling stage; carrying out solution treatment; aging treatment; and machining. Good combination of the steel and the copper alloy is achieved, and the performance of the composite material is remarkably improved.

Description

Technical Field

[0001] The present invention relates to a composite material, in particular to a method for preparing a steel-copper alloy composite material, belonging to the technical field of metal composite material preparation. Background Art

[0002] Steel-copper alloy composite materials have broad application prospects in the fields of aerospace, power electronics, and the automotive industry because they combine the high strength of steel with the excellent thermal conductivity and electrical conductivity of copper alloys. At present, the typical preparation method of steel-copper alloy composite materials is the casting method, which is to cast the molten copper alloy onto the surface of the preheated steel or into the cavity. Although a metallurgical bond can be formed, the large difference in the melting points of steel and copper can easily cause uneven structure at the interface, and the thermal stress during the cooling process can easily lead to cracking or delamination of the interface. In addition, in the casting method, due to the unevenness of the solidification process, macro-segregation of alloy elements can easily occur, and the subsequent heat treatment process is difficult to effectively control grain growth, resulting in coarse grains in local areas.

[0003] Therefore, it is urgent to develop a new method for preparing steel-copper alloy composite materials to improve the interface bonding strength, optimize the microstructure, and enhance the uniformity and stability of material properties. Summary of the Invention

[0004] Based on the above background, the purpose of the present invention is to provide a method for preparing a steel-copper alloy composite material to solve the problems described in the background technology.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] A method for preparing a steel-copper alloy composite material, the method comprising the following steps:

[0007] Raw material preparation: 200-200 kg of steel per batch, 480-500 kg of copper alloy per batch. The mass percentage of each component of the copper alloy is 80-85% electrolytic copper, 7-10% zinc, 1.5-3% aluminum, 1-2.5% manganese, and 0.5-1.5% iron.

[0008] Copper alloy smelting: electrolytic copper, zinc, aluminum, manganese and iron are put into the power frequency induction furnace in proportion, heated to 1150-1200℃, kept warm for 30-40 minutes, and molten copper alloy is obtained after smelting;

[0009] Steel pretreatment: preheat the steel after surface treatment, the preheating temperature is 330℃, and the holding time is 15 minutes;

[0010] Steel copper pouring treatment: put the preheated steel into the mold and cast the molten copper alloy at a casting speed of 0.5-1kg / s. After casting, it is cooled by the staged cooling method. 800℃ to 600℃ is the slow cooling stage, the cooling rate is 5-10℃ / min, and below 600℃ is the fast cooling stage.

[0011] Solution treatment: heating the cooled steel-copper alloy composite material to 850-880°C at a heating rate of 200-250°C / hour for 90-100 minutes, followed by rapid cooling;

[0012] Aging treatment: heating the solution treated steel-copper alloy composite material from room temperature to 460-490°C at a heating rate of 100-150°C / hour for 4.5-5.5 hours, and then air cooling to room temperature at a cooling rate of 50-80°C / hour;

[0013] Machining: Cutting, turning or milling of steel-copper alloy composite materials according to product size requirements.

[0014] Preferably, in the copper alloy smelting, after the electrolytic copper is put into the industrial frequency induction furnace, 0.05-0.1 wt% of phosphor copper is added as a deoxidizer, and then zinc, aluminum, manganese and iron are put into the industrial frequency induction furnace.

[0015] Preferably, in the steel copper pouring process, the mold is a graphite mold, and the mold preheating temperature is 250-300°C.

[0016] Preferably, in the staged cooling method, the cooling curve in the slow cooling stage from 800°C to 600°C follows the following exponential decay function:

[0017] T=T0·e -kt ;

[0018] Where T represents the current temperature, T0 represents the initial temperature, k represents the cooling coefficient, and t represents the cooling time;

[0019] Water mist cooling is adopted in the rapid cooling stage below 600℃, the water mist particle size is 50-100μm, and the atomization pressure is 0.3-0.5MPa.

[0020] Preferably, in the solution treatment, rapid cooling is performed by oil quenching, with the oil temperature being 60 to 80° C. and the stirring speed being 0.5 to 1.0 m / s.

[0021] Preferably, in the aging treatment, heating is performed in a vacuum heat treatment furnace, the vacuum degree is controlled at 0.01-0.1 Pa, air-cooling is performed to room temperature, and argon or nitrogen is introduced as a protective gas at a flow rate of 2-3 L / min.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] The present invention provides a method for preparing a steel-copper alloy composite material. By precisely controlling the raw material ratio, smelting temperature, casting speed, and subsequent heat treatment process, a good combination of steel and copper alloy and a significant improvement in the performance of the composite material are achieved. By optimizing the copper alloy component ratio, in particular, by adding appropriate amounts of aluminum, manganese, and iron, the fluidity of the copper alloy and its wettability with steel are improved, thereby enhancing the interface bonding strength. By adopting a segmented cooling method in the steel copper casting process, the stress distribution during the solidification process is effectively controlled, and the generation of interface defects is reduced. By precisely controlling the temperature, time, and cooling method of the solution treatment and aging treatment, the internal stress of the steel-copper alloy composite material is effectively released, element diffusion is promoted, the interface bonding strength is enhanced, the microstructure of the material is stabilized, and the strength and hardness of the material are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0025] Figure 1 It is a schematic flow chart of a method for preparing a steel-copper alloy composite material of the present invention. DETAILED DESCRIPTION

[0026] The technical solution of the present invention will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings. It should be understood that the implementation of the present invention is not limited to the following embodiments, and any form of modification and / or change made to the present invention will fall within the scope of protection of the present invention.

[0027] In the present invention, unless otherwise specified, all parts and percentages are by weight. The equipment and raw materials used are commercially available or commonly used in the art. The methods in the following embodiments, unless otherwise specified, are conventional methods in the art. The components or equipment in the following embodiments, unless otherwise specified, are all universal standard parts or components known to those skilled in the art. Their structures and principles are known to those skilled in the art through technical manuals or routine experimental methods.

[0028] The present invention discloses a method for preparing a steel-copper alloy composite material, such as Figure 1 As shown, the method includes the following steps:

[0029] Raw material preparation: The steel batch size is 200-200kg, the copper alloy batch size is 480-500kg, and the mass percentage of each component of the copper alloy is 80-85% electrolytic copper, 7-10% zinc, 1.5-3% aluminum, 1-2.5% manganese, and 0.5-1.5% iron.

[0030] Copper alloy smelting: electrolytic copper, zinc, aluminum, manganese and iron are put into the power frequency induction furnace in proportion, heated to 1150-1200℃, kept warm for 30-40 minutes, and molten copper alloy is obtained after smelting;

[0031] Steel pretreatment: preheat the steel after surface treatment, the preheating temperature is 330℃, and the holding time is 15 minutes;

[0032] Steel copper pouring treatment: put the preheated steel into the mold and cast the molten copper alloy at a casting speed of 0.5-1kg / s. After casting, it is cooled by the staged cooling method. 800℃ to 600℃ is the slow cooling stage, the cooling rate is 5-10℃ / min, and below 600℃ is the fast cooling stage.

[0033] Solution treatment: heating the cooled steel-copper alloy composite material to 850-880°C at a heating rate of 200-250°C / hour for 90-100 minutes, followed by rapid cooling;

[0034] Aging treatment: heating the solution treated steel-copper alloy composite material from room temperature to 460-490°C at a heating rate of 100-150°C / hour for 4.5-5.5 hours, and then air cooling to room temperature at a cooling rate of 50-80°C / hour;

[0035] Machining: Cutting, turning or milling of steel-copper alloy composite materials according to product size requirements.

[0036] Example 1

[0037] Raw material preparation: 200 kg of steel (Q235 steel), 490 kg of copper alloy, and the mass percentage of the copper alloy components are: 82% electrolytic copper, 8.5% zinc, 2% aluminum, 2% manganese, and 1% iron.

[0038] Copper alloy smelting: After electrolytic copper is placed in an industrial frequency induction furnace, 0.08wt% phosphor copper is added as a deoxidizer. Zinc, aluminum, manganese, and iron are then added in sequence. The heating temperature is 1180°C and the heat is maintained for 35 minutes. After smelting, a molten copper alloy is obtained.

[0039] Steel pretreatment: After rust removal, pickling and neutralization, the steel is preheated at 330°C and the holding time is 15 minutes.

[0040] Steel copper casting treatment: The preheated steel is placed in a graphite mold with a preheat temperature of 280°C. The molten copper alloy is cast at a rate of 0.8 kg / s. After casting, the steel is cooled in sections. During the slow cooling stage from 800°C to 600°C, the cooling curve follows an exponential decay function:

[0041] T=T0·e -kt ;

[0042] Where T represents the current temperature, T0 represents the initial temperature, k represents the cooling coefficient, and t represents the cooling time.

[0043] Water mist cooling is adopted in the rapid cooling stage below 600°C, the water mist particle size is 75μm, and the atomization pressure is 0.4MPa.

[0044] Solution treatment: The cooled steel-copper alloy composite material was heated to 865°C at a rate of 220°C / hour for 95 minutes, and then rapidly cooled by oil quenching at an oil temperature of 70°C and a stirring speed of 0.8 m / s.

[0045] Aging treatment: The solution-treated steel-copper alloy composite material was placed in a vacuum heat treatment furnace with a vacuum degree controlled at 0.05 Pa. The material was heated from room temperature to 475°C at a rate of 120°C / hour, held at that temperature for 5 hours, and then air-cooled to room temperature at a rate of 65°C / hour. Argon was introduced as a protective gas during the cooling process at a flow rate of 2.5 L / min.

[0046] Machining: Cutting and turning of steel-copper alloy composite materials according to product size requirements.

[0047] Example 2

[0048] Raw material preparation: 205 kg of steel (20# steel), 495 kg of copper alloy, and the mass percentage of the copper alloy components are: 83% electrolytic copper, 9% zinc, 2.5% aluminum, 1.5% manganese, and 0.8% iron.

[0049] Copper alloy smelting: Electrolytic copper is placed in an industrial frequency induction furnace, and 0.06 wt% phosphor copper is added as a deoxidizer. Zinc, aluminum, manganese, and iron are then added in sequence. The heating temperature is 1170°C, and the heat is maintained for 38 minutes to obtain a molten copper alloy.

[0050] Steel pretreatment: After rust removal, pickling and neutralization, the steel is preheated at 330°C and the holding time is 15 minutes.

[0051] Steel copper casting treatment: The preheated steel is placed in a graphite mold with a preheat temperature of 270°C. The molten copper alloy is cast at a rate of 0.7 kg / s. After casting, the steel is cooled in stages. During the slow cooling stage from 800°C to 600°C, the cooling curve follows an exponential decay function:

[0052] T=T0·e -kt ;

[0053] Where T represents the current temperature, T0 represents the initial temperature, k represents the cooling coefficient, and t represents the cooling time.

[0054] Water mist cooling is adopted in the rapid cooling stage below 600°C, the water mist particle size is 85μm, and the atomization pressure is 0.35MPa.

[0055] Solution treatment: The cooled steel-copper alloy composite material was heated to 870°C at a rate of 230°C / hour for 98 minutes, and then rapidly cooled by oil quenching at an oil temperature of 75°C and a stirring speed of 0.9 m / s.

[0056] Aging treatment: The solution-treated steel-copper alloy composite material was placed in a vacuum heat treatment furnace with a vacuum degree controlled at 0.03 Pa. The composite material was heated from room temperature to 480°C at a rate of 130°C / hour, held at that temperature for 5.2 hours, and then air-cooled to room temperature at a rate of 60°C / hour. Nitrogen was introduced as a protective gas during the cooling process at a flow rate of 2.8 L / min.

[0057] Machining: Cutting and milling of steel-copper alloy composite materials according to product size requirements.

[0058] Example 3

[0059] Raw material preparation: 210 kg of steel (45# steel), 500 kg of copper alloy, and the mass percentage of the copper alloy components are: 84% electrolytic copper, 7.5% zinc, 1.8% aluminum, 2.2% manganese, and 1.2% iron.

[0060] Copper alloy smelting: Electrolytic copper is placed in an industrial frequency induction furnace, and 0.09wt% phosphorus copper is added as a deoxidizer. Zinc, aluminum, manganese, and iron are then added in sequence. The heating temperature is 1190°C, and the heat is maintained for 33 minutes to obtain a molten copper alloy.

[0061] Steel pretreatment: After rust removal, pickling and neutralization, the steel is preheated at 330°C and the holding time is 15 minutes.

[0062] Steel copper casting process: The preheated steel is placed in a graphite mold with a preheat temperature of 290°C. The molten copper alloy is poured at a rate of 0.9 kg / s. After casting, the steel is cooled in stages. During the slow cooling stage from 800°C to 600°C, the cooling curve follows an exponential decay function:

[0063] T=T0·e -kt ;

[0064] Where T represents the current temperature, T0 represents the initial temperature, k represents the cooling coefficient, and t represents the cooling time.

[0065] Water mist cooling is adopted in the rapid cooling stage below 600°C, the water mist particle size is 65μm, and the atomization pressure is 0.45MPa.

[0066] Solution treatment: The cooled steel-copper alloy composite material was heated to 875°C at a rate of 240°C / hour for 92 minutes, and then rapidly cooled by oil quenching at an oil temperature of 65°C and a stirring speed of 0.7 m / s.

[0067] Aging treatment: The solution-treated steel-copper alloy composite material was placed in a vacuum heat treatment furnace with a vacuum degree controlled at 0.08 Pa. The composite material was heated from room temperature to 470°C at a rate of 140°C / hour, held at that temperature for 4.8 hours, and then air-cooled to room temperature at a rate of 70°C / hour. Argon was introduced as a protective gas during the cooling process at a flow rate of 2.2 L / min.

[0068] Machining: Cutting, turning and milling of steel-copper alloy composite materials according to product size requirements.

[0069] Comparative Example 1

[0070] The method of Example 1 was followed, but the solution treatment step was omitted, and the aging treatment was performed directly after the copper casting treatment on the steel.

[0071] Comparative Example 2

[0072] The method of Example 2 was followed, but the aging treatment step was omitted, and machining was performed directly after solution treatment.

[0073] Comparative Example 3

[0074] The method of Example 3 was followed, but after the copper casting treatment on the steel, conventional natural cooling was adopted instead of the segmented cooling method, with a cooling rate of about 30° C. / min.

[0075] Comparative Example 4

[0076] The conventional steel-copper alloy composite process using the existing melting casting method includes the following steps:

[0077] Raw material preparation: same as in Example 1.

[0078] Copper alloy smelting: All components are added into the induction furnace for smelting at one time, with a heating temperature of 1200°C and a holding time of 40 minutes.

[0079] Steel pretreatment: After rust removal, the steel can be used directly without preheating.

[0080] Steel copper casting treatment: The steel is placed in a cast iron mold without preheating the mold. Molten copper alloy is cast at a rate of 1.5 kg / s and then naturally cooled to room temperature after casting.

[0081] Heat treatment: The cooled steel-copper alloy composite material was kept at 800°C for 2 hours and then water quenched.

[0082] Machining: Processing according to product size requirements.

[0083] To evaluate the effectiveness of the present invention, the steel-copper alloy composite materials prepared in Examples 1 to 3 and Comparative Examples 1 to 4 were tested for performance. The test items included tensile strength, elongation, hardness, and interfacial bonding strength. The test results are shown in the following table:

[0084] sample Tensile strength (MPa) Elongation (%) Hardness (HV) Interface bonding strength (MPa) Example 1 780 18.5 210 320 Example 2 795 19.2 215 335 Example 3 810 17.8 220 340 Comparative Example 1 720 15.6 185 280 Comparative Example 2 750 16.2 195 295 Comparative Example 3 735 14.8 190 285 Comparative Example 4 680 13.5 175 260

[0085] It can be seen from the above table that the steel-copper alloy composite materials prepared in Examples 1 to 3 of the present invention are significantly better than those in Comparative Examples 1 to 4 in terms of various performance indicators.

[0086] The performance indicators of Comparative Example 1, which did not undergo solution treatment, were all lower than those of Examples 1 to 3, indicating that solution treatment plays an important role in improving material properties. Solution treatment can fully dissolve alloying elements, forming a supersaturated solid solution, providing a good foundation for subsequent aging treatment. Specifically, during the casting and cooling process, due to the different thermal expansion coefficients of steel and copper alloy, large internal stresses are generated at the interface. The cast steel-copper alloy may have component segregation or an uneven grain structure. Solution treatment can effectively release internal stress, promote element diffusion, enhance interfacial bonding strength, and dissolve the secondary phase in the alloy into the matrix, thereby preparing for subsequent aging treatment.

[0087] Although the performance indicators of Comparative Example 2 without aging treatment are better than those of Comparative Example 1, they are still significantly lower than those of Examples 1 to 3, indicating that aging treatment is crucial for further improving material properties. Aging treatment can promote the formation of precipitated phases, strengthen the material matrix, and thus improve strength and hardness. Specifically, aging treatment can further release and balance the residual stress of the steel-copper alloy composite material, stabilize the microstructure of the material, and, through the defined heating temperature, heating rate, and holding time, promote the precipitation of solute atoms in the solid solution in a fine dispersed form, thereby improving the strength and hardness of the material.

[0088] The performance indicators of comparative example 3 without segmented cooling are close to those of comparative example 1. This shows that segmented cooling has an important influence on controlling the microstructure and performance of the material. Segmented cooling can effectively control grain growth and reduce segregation, thereby obtaining a more uniform and fine microstructure. Specifically, a casting speed of 0.5 to 1 kg / s is conducive to the formation of a good metallurgical bond between molten copper and preheated steel, while ensuring the filling speed, avoiding the formation of inclusions and pores caused by excessive casting. The segmented cooling after casting optimizes the microstructure of the steel-copper alloy while ensuring the interface bonding strength through the combination of slow cooling and fast cooling, and reduces the occurrence of defects such as thermal cracking and porosity. Among them, the slow cooling stage helps to control the grain size of the copper alloy and reduce the segregation of alloying elements, and the rapid stage helps to refine the grain structure of the copper alloy, form a saturated solid solution, and reduce precipitation, retaining more solute atoms in the matrix.

[0089] Comparative Example 4, using a conventional melt-cast steel-copper alloy composite process, achieved the lowest performance indicators, demonstrating the superiority of the present invention's segmented cooling, solution treatment, and aging treatment process. Conventional processes struggle to effectively control interfacial bonding and microstructure, resulting in poor material performance.

[0090] In summary, the present method for preparing a steel-copper alloy composite material significantly improves the overall performance of the material through the synergistic effects of staged cooling, solution treatment, and aging treatment. This method not only increases the material's strength and hardness while maintaining good plasticity, but also significantly improves the bonding strength at the steel-copper alloy interface.

[0091] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from the principles of the present invention, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a steel-copper alloy composite material, characterized in that: The method comprises the following steps: Raw material preparation: 200-200 kg of steel per batch, 480-500 kg of copper alloy per batch, the mass percentage range of each component of the copper alloy is 80-85% of electrolytic copper, 7-10% of zinc, 1.5-3% of aluminum, 1-2.5% of manganese, and 0.5-1.5% of iron; Copper alloy smelting: electrolytic copper, zinc, aluminum, manganese and iron are put into the industrial frequency induction furnace in proportion, the heating temperature is 1150-1200℃, the insulation time is 30-40 minutes, and the molten copper alloy is obtained after smelting; Steel pretreatment: preheat the steel after surface treatment, the preheating temperature is 330℃, and the insulation time is 15 minutes; Steel copper casting treatment: put the preheated steel into the mold and cast the molten copper alloy at a casting speed of 0.5-1kg / s. After casting, it is cooled by the segmented cooling method. 800℃ to 600℃ is the slow cooling stage, the cooling rate is 5-10℃ / min, and below 600℃ is the fast cooling stage; Solution treatment: heating the steel-copper alloy composite material after cooling treatment to 850-880°C, with a heating rate of 200-250°C / hour, a holding time of 90-100 minutes, and then rapidly cooling; Aging treatment: heating the solution treated steel-copper alloy composite material from room temperature to 460-490°C, with a heating rate of 100-150°C / hour, holding time of 4.5-5.5 hours, and then air cooling to room temperature, with a cooling rate of 50-80°C / hour; Machining: Cutting, turning or milling of steel-copper alloy composite materials according to product size requirements.

2. The method for preparing a steel-copper alloy composite material according to claim 1, characterized in that: In the copper alloy smelting, after electrolytic copper is put into the industrial frequency induction furnace, 0.05-0.1wt% of phosphor copper is added as a deoxidizer, and then zinc, aluminum, manganese and iron are put into the industrial frequency induction furnace.

3. The method for preparing a steel-copper alloy composite material according to claim 1, characterized in that: In the steel copper casting process, the mold is a graphite mold, and the mold preheating temperature is 250-300°C.

4. The method for preparing a steel-copper alloy composite material according to claim 1, characterized in that: In the step-cooling method, the cooling curve in the slow cooling stage from 800°C to 600°C follows the following exponential decay function, T=T0·e -kt ; In the formula, T represents the current temperature, T0 represents the initial temperature, k represents the cooling coefficient, and t represents the cooling time; In the rapid cooling stage below 600°C, water mist cooling is adopted, the water mist particle size is 50-100μm, and the atomization pressure is 0.3-0.5MPa.

5. The method for preparing a steel-copper alloy composite material according to claim 1, characterized in that: In the solution treatment, rapid cooling is carried out by oil quenching, the oil temperature is 60-80° C., and the stirring speed is 0.5-1.0 m / s.

6. The method for preparing a steel-copper alloy composite material according to claim 1, characterized in that: In the aging treatment, a vacuum heat treatment furnace is used for heating, the vacuum degree is controlled at 0.01-0.1 Pa, and argon or nitrogen is introduced as a protective gas after air cooling to room temperature, and the ventilation flow rate is 2-3 L / min.

Images